Compound telephone



(No Model.)

T. A. WATSON. COMPOUND TELEPHONE.

Patented Jan. 10,1882.

a E m u FETEEs rmwume mr, Washinglnn. n. c.

a UNITED STATES PATENT OFFICE. A

THOMAS A. WATSON, OF EVERETT, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS. I

COMPOUND TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 252,160, dated January 10, 1882.

' Application filed April 29, isso. (No model) To all whom it may concern Be it known that I, THOMAS A. WA'rsomof Everett, county of Middlesexfitate of Massachusetts, have invented an Improvement in Compound Telephone and Exchange Systems,

. of which the following description, in connecbe resorted to to tion with the accompanying drawings, is a specification.

My invention relates to telephoneexchange systems, and has for its object to enable several closed telephonic circuits to pass through a single telephonic instrument independently of one another, so that a subscriber on any of the said circuits may directlycommunicate with an attendant at the said central instrument.

In another application filed with the present I have shown several circuits normally open, or of great resistance, uniting and passing through a central instrument of usual construction, and it was therein stated thatit is im: practicable to thus unite a large number of closed. circuits of usual resistance, owing to the division of the currents among the said circuits. A small number-not morethan ten or fifteen circuits-may center in a single instrumentof usualconstruction. When alarg'er number is desired, as would usually be the case in central-ofiice working, some expedient must prevent too great division of tlie currents.

My present invention consistsin acom'pound telephone in which the diflerent circuits intended to pass through the said telephone have independent helices or coils therein; or, it' desired, a small number of circuits can conveniently pass through the same coils, the whole number being thus divided into groups, each having a separate and independent coil in the compound instrument.

As herein shown, a magnetotelephone with a single permanent magnetis provided with a pole-piece with several independent pole-projections, each provided with a helix or coil, one end of which is connected with one of the subscribers circuits, and the other end of each of the said coils is connected to a common groundwire. The difierent poles are each provided with a diaphragm, andthe whole apparatus is inelosed in a case of the usual form, having a single mouth-piece common to all the diaphragms. The result of this arrangement is a that when a subscriber on any circuit is communicating with the central attendant the effeet on the coil and diaphragm of the compound instrument then in circuit is the same as in a single instrument of usual construction, as the other circuits passing through their own coils receive none of the direct currents from the subscriber speaking, but from the effects of induction and the transmission of sound from the one diaphragm to the others in the said compound instrument the sound will be heard on the other circuits centering in the said instrument, so that a subscriber by listening a moment after he has connected his telephone with the central one can tell whether the central operator is already engaged, and, if so, await his turn.

If desired, the different helices or coils might all be placed around asingle core or pole-piece, in which case the inductive effect would be increased without materially diminishing the strength andeft'ect of the inducing-currents. A novel pole-piece invented by me and formingthe subject of another application filed with the present is well adapted to produce the proper effect in the induction-coils.

Figure 1 is a top view of a compound telephone with four independent poles and helices or coils, the month-piece and cover of the inclosing-case being removed; Fig.2, a side view thereof, the upper part being shown in section on line a: a, Fig. 1, and several of the circuits centering in the said instrument being shown in diagram; and Fig. 3, a view of the bottom thereof, showing the binding-screws for connecting the various circuit-wires. Fig. 4 is a partial plan, showing the divided diaphragm and the plate for holding it in place.

The case a, of usual construction, contains in the handle portion the magnet I), adjusted in the usual manner by the screw 0, and provided at its upper end with a circular plate, d, of soft iron, to which the polepieces 6, surrounded bythe usual helices or coils, f, areattached.

As herein shown,the vibrating plate or diaphragm g has separate circular portions corresponding to the different pole-pieces 6, each such portion being adapted to be vibrated incorrespond with the circular portions of the diaphragm, and itself held between the upper end of the case a and the cover a thereof, screwed on in the usual n1anner,and provided with a mouth-piece, 43, opening into a space above and common to all the vibrating surfaces g. \Vhcn there is not a verylarge number of separate poles e a single diaphragm, supported only at its outer edges between the case a and cover a, maybe used, and it is also obvious that each separate" circuit may be distributed upon all the poles e, in which case each spool f would contain a portion of several circuits, instead of each coil being confined to a single-pole, as herein shown, such an arrangement heightening the inductive effect.

The method of grouping and connecting the circuit is indicated in connection with the compound telephone in Fig. 2. The said telephone has one more binding-screw than the number of independent coilsf,oneof the said bindingscrews, Gr, being connected inside the case a by a wire,4, with one end of each of the said-coils f, the other ends thereofbeing separatelyconnected each .with one. of the bindingscrews l 2 3 4 by wires, aportion of two of which (marked 6 7) is shown. The binding-screw G is connected with the ground, and the screws 1 2 3 4 with the respective circuits or groups of circuits,.connected with the ground at their extremities and passing through the usual subscribers stations. Three such circuits are shown in the group passing to the bindingscrew 1. When a subscriber wishes to communicate with another he closes the circuit to theground through his telephone and listens for a moment to hear whether the centraloperator is talking with another subscriber, and, if not, he immediately tells what is wanted, and the attendant listening at the compound telephone gives the proper direction to have the desired connection made, the different circuits being, connected for intercommunication outside of and thus short-circuiting the coils in the compound telephone in any usual manner.

This invention has been herein described as embodied in a magneto-telephone; but it is obvious that it is equally applicable, at least in part, to a battery-transmitter in which a series of independent electrodes may be simultaneously operated by the same sound-waves received from a single sound-passage. For example, separate electrodes could be combined with each of the circular portions of the diaphragm,just as with the diaphragm of a transmitter of any ordinaryor suitable construction. It is obvious thatmore than one sound-passage i may be used as,t'or instance, one leading to each ear.

I claim- 1. The combination,with a telephone having two or more independent helices,of a series of independent circuits greater in number than said helices and divided into groups, each group being connected with'one of said helices or coils, substantially as described.

2. In a compound telephone, two or more separate helices and cores attached to a baseplate and energized by a common permanent magnet, in combination with means, such as binding-posts, for connecting said helices in separate circuits, substantially as described.

3. The combination, in a compound telephone with two or more separate helices and that the portions are adapted to vibrate independently, as set forth.

In testimony whereof Ihavesigned my name to this specification in the presence of two subscribing witnesses.

THOMAS A. WATSON.

Witnesses J os. P. LIVERMORE, N. E. G. WHITNEY. 

